Internal combustion engines, and particularly four stroke four cylinder in-line engines, produce a secondary unbalance during normal operation. A balancer assembly may be incorporated into the engine to generate a vertical shaking force that offsets the secondary unbalance of the engine.
The balancer assembly may include a pair of parallel and laterally offset balance shafts, i.e., a first balance shaft and a second balance shaft, rotatably supported by a housing. The first balance shaft includes a drive gear coupled to and driven by a crankshaft of the engine. The second balance shaft includes a driven gear in meshing engagement with the drive gear. The first balance shaft and the second balance shaft rotate in opposite directions at twice the crankshaft speed to generate the vertical shaking force.